1. Field of the Invention
The present invention relates to semiconductor structures and to a method of fabricating semiconductor structures. More particularly, embodiments relate to semiconductors having an ultraviolet (UV) blocking layer and to processes for fabricating such semiconductors.
2. Description of the Related Art
As semiconductor device density increases, device geometry has continued to shrink and the dimensional requirements of such devices has become more exacting. Plasma process technology is used in ultra large scale integrated circuit (ULSI) fabrication to meet these demands and provides for improved directionality of etch and deposition and for tighter thermal budget control.
Examples of plasma process technologies include plasma implantation, plasma sputtering, physical vapor deposition (PVD), dry etching and chemical vapor deposition (CVD) such as, for example, plasma assisted chemical vapor deposition (PA CVD), plasma-enhancement chemical vapor deposition (PE CVD) and high-density plasma chemical vapor deposition (HD CVD).
However, the use of plasma processing increases the potential for severe damage of semiconductor devices which may result in deteriorated performance of those semiconductor devices. Also, any ultraviolet electromagnetic radiation (UV) produced during plasma processing may alter the semiconductor device behavior and, in particular, may degrade gate oxide reliability of floating gate transistors.
Page 72 of IEEE Symposium on VLSI Technology Digest of Technical Papers 2002, “Avoiding Plasma Induced Damage to Gate Oxide With a Conductive Top Film (CTF) on PECVD Contact Etch Stop Layer”, by Seung-Chul Song et al. describes the use of a thin undoped silicon layer on a contact etch stop layer in order to reduce plasma-induced damage.
Page 356 of IEEE 99CH36296 37th Annual International Reliability Physics Symposium, San Diego, Calif., 1999, by Shuto et al describes that silicon nitride and silicon oxynitride can be used to reduce plasma-induced damage.
Page 449 of IEEE IEDM97, “Degradation of Deep Sub-Micron Isolation by Vacuum Ultraviolet Radiation from Low Temperature Back End Plasma-Assisted Processes”, by Ashburn et al. describes that plasma processing can also damage isolation oxides. Such isolation oxide damage can be reduced in areas covered by polysilicon.
However, there exists a need to provide an effective ultraviolet blocking layer for fabricating semiconductor devices.